Through deck welding

ABSTRACT

This invention is directed at a drawn-arc welding gun with means for providing a rotary flow of air, or stream of fluid, around the weld area. This invention is also directed at ferrules which are designed to enhance movement of air or fluid around the weld area.

United States Patent 1 1 [111 3,736,401

Shoup 1451 May 29, 1973 [54] THROUGH DECK WELDING 2,491,479 12 1949 Dash..219 98 [75] Inventor:' Thomas E Shoup Amherst, Ohio 2,315,502 4/1943Crecca et al ..2l9/98 [73] Assignee: TRW lnc., Cleyeland, Ohio Prim!!!gfgmilreirfgi F, Siaubly 22 Filed; July 9 1970 Attorney-Allen D.GUlChfiSS, J1.

21 Appl. 190.; 53,368 I [57] ABSTRACT This invention is directed at adrawmarc welding gun I! with means for providing a rotary flow f orFleld of Search 98, Stream of fluid, around the weld area-- invention isI also directed at ferrules which are designed to [56] References cuedenhance movement of air or fluid around the weld UNITED STATES PATENTSarea- 2,790,066 4/1957 Haynes et al ..219/98 3 Claims, 10 DrawingFigures 84 7'8 /B2 I I I 74 F H 72 L ll" 22 Patented May 29, 19733,736,401

4 Sheets-Sheet 2 INVENTOR THOMAS E. SHOUP BY 47 2 ATTORNEY Patented May29, 1973 3,736,401

ASheets-Sheet 5 FIG. 7

ENTOR THOMAS SHOUP BY F|G.8 ATTORNEY Patented May 29, 1973 3,736,401

4 Sheets-Sheet 4 lllflllllllIllllllllllllll IIIIHIHIIHIU FIG. IO

I TNVENTOR THOMAS E. SHOUP yam film 45m ATTORNEY BACKGROUND OF THEINVENTION 1. Field of the Invention This invention is directed at adrawn-arc welder for welding a stud to a steel beam through a galvanizedsteel sheet. Heretofore, it has been extremely difficult if notimpossible to weld this assembly satisfactorily. Although some weldshave been made, they were entirely unsatisfactory for many reasons. Oneof the reasons that the weld is unsatisfactory is that zinc has a lowerboiling point than steel and is still in the gaseous state as the steelsolidifies. If the gas is entrapped by the solidifying steel, it remainswithin the weld metal deposit as porosity. The volatilized zinc alsocauses the welding arc to be very unstable and erratic thereby causingexpulsion of weld metal from the weld area.

2. Description of Prior Art The patents toBrowning, U. S. Pat. No.3,204,075 and U. S. Pat. No. 3,204,076 indicate the use of air at theoperating end of the electric arc torch of the plasma forming gas type.The Browning patents disclose that the airis used to remove moltenmaterial and slag produced by the heat and to clean the inner surface ofthe shell 20.

The patent to Herring, .Ir., U. S. Pat. No. 3,324,277 discloses the useof air at the operating end of a plasma torch to control the depth of acut groove and to remove the molten metal from groove.

The patent to Burgman, U. S. Pat. No. 1,716,614 and patents cited incolumn 1 thereof disclose the use of gases other than air around theweld site to increase dutility of the weld. See also the patent toHobart, U. S. Pat. No. 1,746,081.

None of the cited patents disclose the use of air in a stud weldingoperation or in welding through galvanized steel sheet.

SUMMARY OF THE INVENTION An object of the present invention is toprovide an improved welding gun'for welding a stud to a beam throughgalvanized sheet steel.

Another object of the present invention is to provide the use of astream of air or gas near the beginning and through a portion of thedrawn-arc welding cycle thereby improving the weld between a stud and abeam through galvanized sheet steel.

Another object of the preset invention is to provide ferrule designswhich will direct the air or gas in a swirling path over the weld area.

A further object of the present invention is to provide a ferruleutilizing a serated surface at one end and having cone-shaped groovesproximate the other end to enable the air or gas to flow into the weldarea.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a section of a welding gunshowing the new operating end:

FIG. 2 is an exploded view of the welding gun shown in FIG. 1';

FIG. 3 is a front elevation of the gun shown in FIG.

FIG. 4 is a top plan view of the base of the air foot;

FIG. 5 is a front perspective of a modified form of the ferrule;

FIG. 6 is a rear perspective of a modified formof the ferrule;

FIG. 7 is a top plan view of the ferrule shown in FIG.

FIG. 8 is a bottom plan view of another modified form of the ferrule;

FIG. 9 is a bottom plan view of the ferrule shown in FIG. 7; and

FIG. 10 is a diagrammatic representation of the welding gun with allaccessory connections showing a control unit, a power unit and thesolenoid valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT The basic welding tool can beany of a number of suitable types. Where the stud is to be welded by thedrawn-arc method, the tool must include means for retracting the studfrom the workpiece and means for 'moving the stud toward and against theworkpiece.

Means are also provided for holding the stud in a retracted positionuntil it is again. moved toward and against the workpiece. The weldingtool 10 includes a main body or housing 12 of a dielectric material. Thebody 12 has an integral pistol grip l4 and a separable rear end cap 16.A stud holder or chuck 18 is located at the front of the'tool and holdsa stud during the welding operation. A ferrule holder assembly 20 liesin front of the chuck 18 and is adjustably supported by two legs 22. Thechuck 18 is attached to a chuck leg 24, which in turn is attached to apiston shaft 26 which is attached to the intermediate portion 30.

Attached to the intermediate portion 30 is a rod holding element 32,which is integral with a cylindrical lift rod 34 having a cylindricalsmaller diameter guide rod 36 extending rearwardly therefrom through amovable core 38. l

A lifting hook 40 is attached to the movable core 38 and is positionedto engage a lifting ring 42 when moved rearwardly by the movable core38. The ring 42 has an inner diameter slightly exceeding the outerdiameter of the lift rod 34 and the ring 42 is maintained in aperpendicular position to the axis of the rod holding element 32 by alifting ring 42 against a stop plate 46 that is held in place by setscrews. The lifting rod assembly is held in the forward position by areturn or plunge spring 48. In this position the lifting ring 42 is freeof the lift rod 34 which can move rearwardly therethrough when the studand the chuck 18 are moved from an extended position to a positionslightly removed from the initial welding position at the time the studis pressed against the workpiece. This initial welding position may varyslightly for variations in the length of the stud held by the chuck.When the lifting hook 40 engages the lifting ring 42, the ring moves toa position in which it engages the lifting rod 34 and retracts it to afully retracted position when the core 38 moves toward the rear. In thismanner the stud and the chuck will be retracted a predetermined distanceeven though the length of the stud in the chuck may differ from thelengths of other studs.

The movable core 38 is retracted when current is supplied to a solenoidcoil 50 through suitable leads 52 in a manner well known in the art. Therearward movement of the core 38 which determines the extent of the liftof the stud and the chuck is limited by an adjustable core piece 54which can be turned toward or away from the movablecore 38 to vary thelength of the lift stroke.

A terminal of the main welding cable 56 is engaged to the chuck leg 24to hold the terminal against the chuck 18. The other end of the chuckleg 24 engages the piston shaft 26 of the plunge damper assembly 62. Arubber bellows 58 protects the piston shaft 26. An externally threadedstud extends from the intermediate portion 30 for engaging the plungedamper assembly 62. The intermediate portion 30 is also engaged to therod holding element 32.

The ferrule holder assembly includes a foot bracket 65 which has aninternally threaded hole 63 having threads engaged to an externallythreaded element 64 which in turn can be connected to a fluid line foraccepting air, oxygen or other appropriate fluids. The threaded hole 63extends through the bracket 65 and opens into a counter bore in a rightangle support 66. The counter bore is formed through the first leg ofthe right angle support 66 and a passage 68 is formed through the secondleg of the right angle support 66 which is joined by a channel 70completing the system. The air foot 72 is formed of two pieces, an arcedcover having a base 74 including an air hole 76 which mates with thepassage 68 and acts as a continuation thereof, and a C-shaped ferruleholder 78. The air hole 76 opens into a plenum chamber 80 in the upperportion of the cover which has three inlet channels 82 extendingtherefrom opening into three cross-drilled aspiration channels 84 whichextend from the outer surface of the ferrule holder to the inner areathereof. The aspiration channels 84 are of larger diameter than theinlet channels 82 causing a quantity of air to be sucked downtherethrough keeping the oxygen from escaping back up the aspirationchannels 84. The aspiration channels 84 can also be used for passing abrush therethrough for easy cleaning. The aspiration channels 84 are inangular relation to the axis of the gun thereby providing a swirling orcyclonic effect to the air streams.

A stud 86 is loaded into the chuck 18 and a ferrule 88 is inserted inthe C-shaped ferrule holder 78 with the stud 86 extending through theferrule 88. The ferrule 88 is a ring shaped ceramic element having achamfered edge at one end and a serrated edge at the other. Thechamfered edge of the ferrule 88 allows the gases to circle around theweld area of the stud 86 and the serrations allow the gases andcontaminants to be expelled from the weld area. To start the weld cycle,the gun is placed against the workpiece which comprises a strip ofgalvanized steel 90 on a steel beam 92 and the trigger is depressedactivating the control unit 94 from power supplied by the power unit 95.The control unit 94 includes a circuit which causes the stud 86 to belifted from the workpiece and another circuit which causes a solenoidvalve 96 to open allowing air or other gas to be directed into the weldarea through the hole 63 in the bracket 65 thence through the channeland the passage 68 in the right angle support 66; then through the airhole 76 into the plenum chamber 80, out the ferrule holder inlet channel82 and finally through the aspiration channel 84 to the weld area. Aftera predetermined time, an adjustable timing circuit in the control unit94 causes the solenoid valve 96 to shut off and the weld cycle continuesin a manner known in the art.

Another type of ferrule 88a is shown in FIGS. 5 and 6, comprising a ringlike ceramic element having one edge serrated into a saw-toothconfiguration and the other edge with three entry ports 98 formed 120from each other. Each of the ports 98 open into a coneshaped channelwhose apex terminates in the port.

Another type of ferrule 88b has one edge which is chamfered and theother edge which is serrated. Each of the serrations has a surface 100in angular relation to the axis of the ferrule thereby aiding thecircular movement of the air stream.

With reference to the foregoing description it is to be understood thatwhat has been disclosed herein represents an embodiment of the inventionand is to be construed as illustrative rather than restrictive in natureand that the invention is best described by the following claims:

1. In a stud welding tool for welding a stud to a workpiece by a drawnarc, the tool comprising a chuck for holding a stud, means forretracting the chuck, means for supplying welding current to the chuckafter movement of the chuck to the retracted position, and means forplunging the chuck forwardly toward the workpiece after a period of timein the retracted position and a ferrule holder assembly defining an areaand including a foot having a hole formed therein, a plenum chamber intowhich the hole opens, and a series of inlet channels opening into theplenum chamber, and the ferrule holder assembly including aspirationchannels which open into the area defined by the ferrule holder assemblyand which open into the area exterior of the ferrule holder assembly atpoints on the periphery of the ferrule holder assembly and each of theaspiration channels connected to an inlet channel.

2. A stud welding tool as set forth in claim 1 wherein the aspirationchannels are of larger diameter than the inlet channels.

3. A stud welding tool as set forth in claim 2 wherein the aspirationchannels are in angular relation to the axis of the ferrule holderassembly.

1. In a stud welding tool for welding a stud to a workpiece by a drawnarc, the tool comprising a chuck for holding a stud, means forretracting the chuck, means for supplying welding current to the chuckafter movement of the chuck to the retracted position, and means forplunging the chuck forwardly toward the workpiece after a period of timein the retracted position and a ferrule holder assembly defining an areaand including a foot having a hole formed therein, a plenum chamber intowhich the hole opens, and a series of inlet channels opening into theplenum chamber, and the ferrule holder assembly including aspirationchannels which open into the area defined by the ferrule holder assemblyand which open into the area exterior of the ferrule holder assembly atpoints on the periphery of the ferrule holDer assembly and each of theaspiration channels connected to an inlet channel.
 2. A stud weldingtool as set forth in claim 1 wherein the aspiration channels are oflarger diameter than the inlet channels.
 3. A stud welding tool as setforth in claim 2 wherein the aspiration channels are in angular relationto the axis of the ferrule holder assembly.